cool java programs

Configuring variables for the Java environment1. Download and install the JDK2. Right-click on "My Computer" → properties → advanced system settings → environment variable changes:A: The value of the input variable name (java_home) variable in the new (paste the installation path of the JDK: location)B: System variable opens path, variable value increases "%java_home%bin/;"3. Test: Start →cmd→java-version→

A small problem with running Java programs in linux-general Linux technology-Linux programming and kernel information. For more information, see the following. It is okay to run java hello on linux, but it is impossible to run a complicated program. An error is reported to indicate noclass ××× or something. Check the path settings. Next, we add the jdk inst

result is "3 apples", the other form similar to the following calculation:String str1 = (1 + 2) + "apples";For STR2 strings, since the first one involved is a string type, the result of adding 1 is "apples 1", which is still a string and then added to 2, and the result is a string, also known as "APPLES12". This means that if the first argument is a string, all subsequent computations will be converted to string type, who makes the string the eldest!　Note: in the "+" expression, the string stri

0:iload_0 1:iload_1 2:iadd 3:ireturn linenumbertable: Line 18:0 public static int MethodB (int, int); Signature: (II) I flags:acc_public, Acc_static code:stack=2, locals=2, args_size=2 0:iload_0 1:iload_1 2:isub 3:ireturn linenumbertable: Line 22:0 public static int methodc (int, int); Signature: (II) I flags:acc_public, Acc_static code:stack=2, locals=2, args_size=2 0:iload_0 1:iload_1 2:imul 3:ireturn l

the processor can support. Unlike high-level interfaces, which can only use PAPI prefabricated events, the PAPI interface can monitor the processor hardware behavior of the program at run time directly using native events. A user can compose one or more native events into an event set, then, by setting the hardware performance counter, all the native events in the Event group are monitored simultaneously, and then the performance problems of the program are analyzed according to the monitoring

can be drawn: The sign bit is 0, the power exponent is the shift code representation, both are equal. The only difference is the mantissa.The mantissa in the double is: 001100010110011110010111 0000000000000000000000000000, omitting the subsequent 0, which requires at least 24 bits to be correctly represented.And the mantissa below float is: 00110001011001111001100, total 23 bits.Why is that? The reason is obvious, because the float mantissa can only represent 23 bits, so the 24-bit 00110001011

check if there are objects in memory that can be recycled, which is risky for an application, and if it is a Web application, all requests are paused, waiting for the garbage collector to execute, if the heap memory The object is also acceptable, but the object is more (now the Web project is bigger, the framework, tools are more and more, loaded into the memory of the object of course more), the process is very time-consuming, may be 0.01 seconds, it may be 1 seconds, or even 20 seconds, which

JDBC Connection Database The programming involved in building a JDBC connection is fairly straightforward. Here are the simple four steps: Import JDBC Package: Add import statements to Java Program import required classes in Java code. Registering the JDBC driver: This step will cause the JVM to load the required drivers into memory so it can implement the JDBC request. Database URL formulatio

Original: Share very useful Java programs (key code) (ii)---list files and directories File dir = new file ("DirectoryName"); String[] Children = dir.list (); if (children = = null) {//either Dir does not exist or was not a directory} else {for (int i=0; I l T Children.length; i++) {//Get filename of file or directory String filename = children[i]; }}//It is also possible to filter t

The Java Java.lang.Runtime class provides a way to run the Windows CMD Environment, exec (String command), and all programs executed under the Windows CMD Command window can be executed using this method.The following two encapsulated code is provided below, one is to see if the program is running, and the other is to start the program:1. Check if the program is running: where tasklist/fi "IMAGENAME eq proc

Write high-quality code: 151 recommendations for improving Java programs--[52~64] recommended use of String direct value assignmentJava in order to avoid a large number of string objects in a system (why a large number of production, because the string string is the most commonly used in the program), so the design of a string pool (also known as a string constant pool, string pool or string Constant Pool o

Java implements the desktop shortcut source code for Automatic startup and creation of software programs at startup. One click javareal.exe automatically starts when the program is started. 1. Description In the java project compiled by eclipse, use exe4j wizardto package an. EXE executable file and enable the user to start automatically at startup. 2. Steps 1.

In one of the previous blogs I wrote about the sequence of initialization of programs in a class, but in Java object-oriented, there are still inheritance relationships between classes. So about the initialization order of the program, we can be subdivided into: The parent class static variable, the parent class static code block, the parent class constructor, the parent class non-static variable, the paren

DemandOracle calls third-party external programs. Oracle uses SQLULDR2 to quickly export large quantities of data and then use WinRAR to compress and send messages.This document mainly implements the first two steps, the sending mail program is no longer explained here.Original codeAuthorizedBegin Dbms_java.grant_permission (' SCOTT ', ' SYS:java.io.FilePermission ', ' Begin Dbms_java.grant_permission (' SCOTT ', ' java.lang.RuntimePermission ', ' * '

Tomcat + java web programs continue to occupy cpu issues for debugging Symptom: Deploy Java web applications in tomcat. After a while, the java Process of tomcat continues to occupy up to 100% of the cpu, leading to blocked web application access. Possible Cause Analysis: The program may indeed perform data computing;

Java continue break creates simple chat room programs to shield uncivilized languages and display the chat time of each sentence. Simple chat rooms are uncivilized. Package com. swift; import java. text. simpleDateFormat; import java. util. date; import java. util. listener;

coordinate array. viewplaincopytoclipboardprint? intposX[]={70,64,26,32,176,170,208,214}; This definition cannot obtain real data on a real machine, The global variable is initialized to 0, It is not intuitive to assign values to a method. For example voidinit_arena_data() { posX[0]=70;posX[1]=64;posX[2]=26;posX[3]=32;posX[4]=176;posX[5]=170;posX[6]=208;posX[7]=214; ｝ These data cannot be initialized and assigned values, so it is difficult to use constants to describe

Eclipse is an integrated development environment (IDE), which is an auxiliary development software, itself open source, can be directly to the official website to download, note the version: http://www.eclipse.org/downloads/Download unzip to use without installationDevelopment process:First step: Create a Java projectStep Two: Create a packageStep three: Write Java source programFourth step: Running

Simple Example of accessing Java classes from Python programs, pythonjava from jnius import autoclass>>> Stack = autoclass('java.util.Stack')>>> stack = Stack()>>> stack.push('hello')>>> stack.push('world')>>> stack.pop()'world'>>> stack.pop()'hello' In the above Code, we use the autoclass function to create a type proxy, which corresponds to all the methods and field attributes of the

Background:Group has engaged in a book meeting, I am the person in charge, we study the topic is Java, in order to better serve the book meeting, so arrange a study plan, then at the book meeting to do share.This is the second reading Conference, the first time to talk about some basic Java knowledge, this time as long as learning objects.Learning content:Various operators of the 1,javaThe modifiers of the